Credit Quality And Allowance For Credit Losses (Loan Modifications Made to Borrowers Experiencing Financial Difficulty) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 162
Percent of Total Class	0.31%
Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 118
Payment Delay
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	20
Interest Rate Reductions
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	11
Other Modifications
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	13
Business loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 159
Percent of Total Class	0.33%
Business loans | Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 117
Business loans | Payment Delay
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	20
Business loans | Interest Rate Reductions
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	10
Business loans | Other Modifications
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	12
Business loans | Commercial | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 124
Percent of Total Class	0.46%
Business loans | Commercial | Commercial mortgage | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 25
Percent of Total Class	0.18%
Business loans | Commercial | Commercial mortgage | Other business lines | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 25
Percent of Total Class	0.28%
Business loans | Commercial | Real estate construction | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 10
Percent of Total Class	0.19%
Business loans | Commercial | Real estate construction | Other business lines | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 10
Percent of Total Class	1.92%
Business loans | Commercial | Term Extension | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 92
Business loans | Commercial | Term Extension | Commercial mortgage | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	15
Business loans | Commercial | Term Extension | Commercial mortgage | Other business lines | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	15
Business loans | Commercial | Term Extension | Real estate construction | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	10
Business loans | Commercial | Term Extension | Real estate construction | Other business lines | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	10
Business loans | Commercial | Payment Delay | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	20
Business loans | Commercial | Payment Delay | Commercial mortgage | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Business loans | Commercial | Payment Delay | Commercial mortgage | Other business lines | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Business loans | Commercial | Payment Delay | Real estate construction | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Business loans | Commercial | Payment Delay | Real estate construction | Other business lines | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Business loans | Commercial | Interest Rate Reductions | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	10
Business loans | Commercial | Interest Rate Reductions | Commercial mortgage | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Business loans | Commercial | Interest Rate Reductions | Commercial mortgage | Other business lines | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Business loans | Commercial | Interest Rate Reductions | Real estate construction | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Business loans | Commercial | Interest Rate Reductions | Real estate construction | Other business lines | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Business loans | Commercial | Other Modifications | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	2
Business loans | Commercial | Other Modifications | Commercial mortgage | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	10
Business loans | Commercial | Other Modifications | Commercial mortgage | Other business lines | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	10
Business loans | Commercial | Other Modifications | Real estate construction | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Business loans | Commercial | Other Modifications | Real estate construction | Other business lines | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Retail loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 3
Percent of Total Class	0.07%
Retail loans | Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 1
Retail loans | Payment Delay
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Retail loans | Interest Rate Reductions
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	1
Retail loans | Other Modifications
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	1
Retail loans | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 3
Percent of Total Class	0.13%
Retail loans | Consumer | Home equity | Other business lines | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 3
Percent of Total Class	0.16%
Retail loans | Consumer | Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 1
Retail loans | Consumer | Term Extension | Home equity | Other business lines | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	1
Retail loans | Consumer | Payment Delay
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Retail loans | Consumer | Payment Delay | Home equity | Other business lines | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Retail loans | Consumer | Interest Rate Reductions
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	1
Retail loans | Consumer | Interest Rate Reductions | Home equity | Other business lines | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	1
Retail loans | Consumer | Other Modifications
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	1
Retail loans | Consumer | Other Modifications | Home equity | Other business lines | Domestic loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 1